JPS5892198A - Dynamic speaker - Google Patents

Abstract

PURPOSE:To simultaneously drive nodes of different oscillation modes, by driving one side of a rectangular flat diaphragm and asymmetrically arranging an edge member to support the diaphragm to a frame from the center position of the diaphragm. CONSTITUTION:A magnetic circuit consisting of a magnet 4, a yoke 5, and a center pole 6 is fitted to a frame 3, and a bobbin 8 having a voice coil 9 is supported to the frame 3 with a damper 7 so that a voice coil 9 makes piston movement in a magnetic gap between the yoke 5 and the center pole 6 constituting the magnetic circuit. An edge member 10 can be formed that a short side of a diaphragm 1 near the driving position is narrow, a short side apart from the drive position is wide, and a long side has narrow shape the same as the short side near the drive position. Thus, the 2nd and 3rd order harmonic distortion can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrodynamic speaker in which a rectangular plane diaphragm is driven by a single voice coil, and its purpose is to produce even sound up to the high range. An object of the present invention is to provide an electrodynamic speaker that can obtain high frequency characteristics and reduce distortion.

Generally, an electrodynamic speaker in which a rectangular plane diaphragm is driven by one voice coil is constructed as shown in FIG. In FIG. 1, a rectangular plane diaphragm 1 is supported at its outer periphery by a frame 3 via an edge member 2, and the frame 3 is attached to a magnetic circuit formed by a magnet 4, a yoke 6, and a center ball 6. There is. A bobbin 8 having a voice coil 9 supported by a damper 7 bonded to one side of the frame 3 is directly bonded to the lower surface of the rectangular plane diaphragm 1. As shown in FIG. 1, when one voice coil bobbin 8 is directly bonded to the diaphragm 1 and the diaphragm 1 is centrally driven by only one magnetic circuit, a vibration mode as shown in FIG. 2 occurs. Here, A indicates a vibration mode at the first resonance frequency C, and in this vibration mode A, two nodes a and a' substantially parallel to the short side of the diaphragm 1 are generated.

B indicates a vibration mode at the second resonance frequency 12, and in this vibration mode B, three nodes, b' and b'/, approximately parallel to the short side of the diaphragm 1 occur.

C indicates a vibration mode at the third resonance frequency f3, and in this vibration mode C, four nodes c, c', c", C" substantially parallel to the short side of the diaphragm 1 are generated. As explained above, when driven by the center drive method shown in FIG. 1, the high frequency reproduction limit is determined by the divided resonance of the diaphragm 1, so unevenness as shown in FIG. 3 occurs. This results in sound pressure frequency characteristics. Therefore, the fourth
As shown in FIG. 6, it has been proposed to flatten the sound pressure frequency characteristics by moving one voice coil bobbin 8 to one short side of the diaphragm 1 and driving it in a nodal manner.

In FIGS. 4 and 5, a rectangular plane diaphragm 1 is supported at its outer periphery by a frame 3 via an edge member 2,
Magnet 4 on one side of frame 30. A magnetic circuit consisting of a yoke 6 and a center pole 6 is attached, and a bobbin 8 having a voice coil 9 supported by a damper 7 is directly bonded to the frame 3 at the position of a node occurring in the rectangular plane diaphragm 1. At this time, the voice coil bobbin 8 is located at two nodes: node a', which is generated by the voice coil bobbin 8, and node C, which is generated by the third resonance frequency 13, and the voice coil bobbin 8 is large enough to directly drive these two nodes at the same time. By using the nodal drive method as described above, as shown in Fig. 6, the characteristics when using the center drive method (the characteristics of the unevenness shown by the broken line) can be improved as shown in red. In other words, the characteristics can be improved so that the sound pressure characteristics have fewer peaks and troughs due to resonance of the diaphragm.Another driving method is shown in Figure 2. The same effect could be obtained even if the method of combining the positions of the various parts shown in Fig. 1 was changed.
In the case of direct connection to a 1-point coil bobbin, as shown in FIG. 7, there was a drawback that distortion due to second and third harmonics increased. The reason for these is thought to be that rolling is more likely to occur due to one-sided drive compared to the conventional case where two magnetic circuits are used and driven symmetrically at two locations.

The present invention solves these conventional drawbacks,
The edge member for driving the rectangular plane diaphragm on one side and supporting the rectangular plane diaphragm on the frame is configured to be asymmetrical when viewed from the center position of the rectangular plane diaphragm. According to this configuration, not only can a flat sound pressure frequency characteristic up to high frequencies be obtained because nodes of different vibration modes are simultaneously driven, but also an asymmetric edge can be obtained even when driven by a single voice coil. This has the advantage that it is possible to further reduce the rolling phenomenon, and thereby also to reduce strain.

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 8 and 9 are a top view and a structural sectional view of the electrodynamic speaker of the present invention as seen from the side.

In FIG. 8, reference numeral 1 denotes a rectangular plane diaphragm, which is supported on a frame 3 via an edge member 1o whose outer periphery is asymmetrically shaped (different edge widths). As shown in FIG. 9, the diaphragm 1 prototyped using the asymmetric edge member 1o is directly bonded to the voice coil bobbin 8 so that it can be driven using a one-sided drive system (nodal drive system). In other words, magnet 4. A magnetic circuit consisting of a yoke 6 and a center pole 6 is attached to the frame 3, and the voice coil 9 is provided so that the voice coil 9 makes a piston movement within the magnetic gap between the yoke 6 and the center pole 6 that constitute the magnetic circuit. bobbin 8 damper 7
It is supported on frame 3 at . The edge member 1o has a shape in which the short side of the diaphragm 1 close to the drive position is narrow, the short side far from the drive position is wide, and the long side is narrow enough to support the short side close to the drive position. It is formed to have.

In this way, by making the shape of the edge member asymmetric, reducing the edge width on the voice coil driving side and increasing the edge width on the opposite side, the second and third It has become possible to significantly reduce the harmonic distortion of This is because the edge width on the voice coil drive side is made smaller than the edge width on the opposite side, suppressing the amplitude on the voice coil side, and making it easier to vibrate on the opposite side, making it difficult for the low rift phenomenon to occur. This is to become.

In addition, as shown in FIG. 11, the shape of the edge width is formed so that it becomes gradually larger as it goes from the voice coil drive l1J1+1J to the opposite side.
It goes without saying that the same strain reduction effect as described above can be obtained even when the diaphragm is supported on the frame.

As described above, according to the present invention, there is provided nine voice coil bobbins that simultaneously touch two nodes in different vibration modes among the vibration modes of free vibration of a rectangular plane diaphragm, and a magnetic circuit is provided on the bobbin. The rectangular plane diaphragm is configured such that the rectangular plane diaphragm is nodally driven by the voice coil that makes a piston movement within the gap, and the outer periphery of the rectangular plane diaphragm is arranged so that the short side of the rectangular plane diaphragm near the driving side of the voice coil is narrow and Since the voice coil is configured to be supported on the frame by an asymmetrical edge member whose short side is wide, it is possible to suppress the occurrence of rolling of the rectangular plane diaphragm and reduce distortion. It also has the advantage of being able to expand the reproduction band as a flat sound pressure frequency characteristic. Moreover, the magnetic circuit, that is, the voice coil, is one
Because of this, it has the advantage of having a good space factor and being optimal as a small speaker.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the structure of a flat-plate speaker when driven by the center, Figure 2 is a diagram showing the vibration mode of the diaphragm and the positional relationship of the nodes when driven by the center, and Figure 3 is the sound pressure of the same speaker. Frequency characteristic diagram, Figure 4 is a top view of a conventional nodal drive type speaker, Figure 6 is a structural sectional view of the same speaker, Figure 6 is a sound pressure frequency characteristic diagram of the same speaker, and Figure 7 is a diagram of the same speaker. FIG. 8 is a top view showing an embodiment of the speaker of the present invention, FIG. 9 is a structural sectional view of the same speaker, FIG. 10 is a distortion characteristic diagram of the same speaker, and FIG. 11 is a diagram of the speaker according to the present invention. FIG. 7 is a top view showing another embodiment of the speaker. 1-...Rectangular plane diaphragm, 3...Frame, 4...Magnet, 6-Old...Yoke, 6
... Center pole, 7 ... Damper, 8 ... Voice coil bobbin, 9 ...
Voice coil, 1o...self...edge component. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
, Figure 3, Figure 4, Figure 6, Figure 8, Figure 9, Figure 10

Claims (1)

[Claims] The rectangular plane diaphragm has a voice coil bobbin that simultaneously touches two nodes in different modes of free vibration of the vibration mode of the free vibration, and the voice coil that is separated by this bobbin and moves as a piston within the gap of the magnetic circuit produces the above-mentioned The rectangular plane diaphragm is configured to be nodal driven, and the outer periphery of the rectangular plane diaphragm is wider on the short side farther from the voice coil drive part than the short side closer to the voice coil drive part. An electrodynamic speaker configured to be supported by a frame using asymmetric edge members.